SPL De-Esser - Auto-Dynamic De-Esser

The SPL De-Esser is a highly specialised audio tool for removing undesired sibilant frequencies in a very simple and musical way without compromising the timbre and natural character of a voice.

To solve this difficult problem, SPL has developed a new circuit design that combines ease of use with natural sound characteristics and the highest level of technical performance. The SPL De-Esser monitors the S-frequency spectrum and automatically detects the sibilant frequencies. The de-ess bandwidth is set so narrowly around the range of the sibilance that neighbouring frequencies remain unaffected. Input processed via this frequency band is mixed back into the main signal phase-inverted so that only the S-sounds are cancelled where the S-reduction controller determines the intensity of the phase-cancelled mix. The result is a neutral, unobtrusive and extremely effective de-essing process. Even at high S-reduction values the de-essing has a negligible effect on the character and timbre of the voice.

Rounding out the amazingly simple control system is an automatic threshold-adjusting function. Differences in the input level caused by the varying distance to the mic, are compensated for automatically. This ensures even de-essing independent of signal level so any necessary compression may be applied post the de-esser.

Traditional de-essers use compression techniques. In addition to the threshold parameter used to set the processing level, there is a frequency controller for setting the center frequency of the process (with bandwidths generally up to 4 kHz). Processing therefore compresses the entire selected range, not just the sibilant or S sounds. This results in the familiar and undesired side-effects such as lisping and a nasal-sounding vocal.

SPL’s Auto Dynamic De-Esser monitors the entire frequency spectrum and automatically detects the sibilant frequencies. The bandwidth is set so narrowly around the range of the sibilance that neighboring frequencies remain unaffected. This frequency band is mixed back into the main signal phase-inverted to cancel out the sibilance. The result is a sound-neutral, inconspicuous and extremely effective process. Even at high s-reduction values the de-essing has an egligible effect on the character and timbre of the voice.Auto-Threshold

Rounding our this outstanding concept is an automaticthreshold-adjusting function: Differences in the input levelcaused by the singer moving in relation to the microphone are automatically compensated, so that the selected reduction value remains constant. In traditional de-essers, the processing intensity drops off with increasing distance, and compressors placed after the de-esser for signal correction tend to respond incorrectly to the changed values.Male/Female

The SPL system doesn’t just look for sibilance in a wide ’general sibilance’ region of the spectrum. Instead, the user simply sets a front-panel switch to Male or Female to adjust for the vocal characteristics of male or female voices.Features